Flashcards in Corneal Function Deck (39):
What are the primary functions of the cornea?
-protects the internal parts of the eye
What are the factors that affect refraction?
-curvature of the anterior surface
-curvature of the posterior surface
-change in refractive index from air to cornea
-change in refractive index from cornea to aqueous
What is the total power of the eye?
What is the power of the cornea?
The cornea is __ the power of the eye
2/3 to 3/4
We want ___scattering, _____ distortion, and ___ transmission
What are the 5 keys to maximize light transmission?
-smooth optical surface
-regular surface of epithelial cells
-absence of blood vessels
-correct spatial arrangement of collagen fibrils in the stroma
-less than 1% light scatter
T/F: the cornea is one of the most sensitive tissues in the body
Where is the cornea most densely innervated?
What nerve supplies the cornea?
Ophthalmic division of the trigeminal nerve
What is the normal CV of endothelium?
What shape of endothelial cells?
T/F: endothelial cells grow back
False. Once they are gone, they are gone
The stroma makes up ___%of the cornea
What is the regular size of collagen fibrils and the spacing?
And why is this important
Important for corneal transparency
The corneal transparency is optimal when the stroma is ____ water
Tough layer of collagen and laminin that protects the underlying layers
In PRK what layer do you destroy?
What type of junctions does corneal epithelium have?
This layer has anionic proteoglycans that pull water in
This layer of the cornea slowly leaks fluid into the cornea
Corneal hydration is dependent on?
-barrier function of epithelium and endothelium
-water and ion transport
What are the major driving forces or water transport across epithelium and endothelium?
Cl- extrusion and Na absorption
Small integral membrane proteins residing in the plasma membrane
What are some roles of aquaporins?
What does high IOP do to water?
It can move excessive water into the stroma from the anterior chamber and overwhelm the endothelial transport system
A minor abrasion of the epithelium causes the loss of?
What are 2 results of a corneal abrasion?
What does an epithelial edema do to VA?
When do corneal abrasion often heal?
When can epithelium be replaced?
In 2 weeks
What are the 3 required nutrients of the cornea?
The endothelium and endothelial consumes most of what nutrient?
Inflammatory or infective condition that compromises the integrity of the epithelium.
Are the epithelium and endothelium hydrophobic or philic?
T/F: epithelium is impermeable to ions
T/F: lipid soluble materials can generally penetrate the cornea more easily
Are the nerves in the cornea Myleinated or non?